Evaluation of a method for reducing unlicensed driving: the Washington and Oregon license plate sticker laws

This report covers an evaluation of programs designed to reduce unlawful driving in the states of Washington and Oregon by providing for the marking of the license plate of a vehicle when its operator was apprehended driving while suspended. In both states, the records of 101,000 drivers convicted of a drunk-driving offense who were potentially at risk for this sanction were analyzed using time series analysis to determine the general deterrent effect of the law. In addition, the specific deterrent effect of having one's vehicle marked was studied in Oregon using analysis of covariance. Results of these analyses indicated that the law had both a general and specific deterrence effect in Oregon but no measurable effect in Washington.